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Annotation of XNU/bsd/kern/qsort.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * The contents of this file constitute Original Code as defined in and
        !             7:  * are subject to the Apple Public Source License Version 1.1 (the
        !             8:  * "License").  You may not use this file except in compliance with the
        !             9:  * License.  Please obtain a copy of the License at
        !            10:  * http://www.apple.com/publicsource and read it before using this file.
        !            11:  * 
        !            12:  * This Original Code and all software distributed under the License are
        !            13:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            14:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            15:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            16:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            17:  * License for the specific language governing rights and limitations
        !            18:  * under the License.
        !            19:  * 
        !            20:  * @APPLE_LICENSE_HEADER_END@
        !            21:  */
        !            22: /*
        !            23:  * Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved
        !            24:  *
        !            25:  * Copyright (c) 1992, 1993
        !            26:  *     The Regents of the University of California.  All rights reserved.
        !            27:  *
        !            28:  * Redistribution and use in source and binary forms, with or without
        !            29:  * modification, are permitted provided that the following conditions
        !            30:  * are met:
        !            31:  * 1. Redistributions of source code must retain the above copyright
        !            32:  *    notice, this list of conditions and the following disclaimer.
        !            33:  * 2. Redistributions in binary form must reproduce the above copyright
        !            34:  *    notice, this list of conditions and the following disclaimer in the
        !            35:  *    documentation and/or other materials provided with the distribution.
        !            36:  * 3. All advertising materials mentioning features or use of this software
        !            37:  *    must display the following acknowledgement:
        !            38:  *     This product includes software developed by the University of
        !            39:  *     California, Berkeley and its contributors.
        !            40:  * 4. Neither the name of the University nor the names of its contributors
        !            41:  *    may be used to endorse or promote products derived from this software
        !            42:  *    without specific prior written permission.
        !            43:  *
        !            44:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            45:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            46:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            47:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            48:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            49:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            50:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            51:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            52:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            53:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            54:  * SUCH DAMAGE.
        !            55:  *
        !            56:  *     @(#)qsort.c     8.1 (Berkeley) 6/4/93
        !            57:  */
        !            58: 
        !            59: 
        !            60: #include <sys/types.h>
        !            61: #include <stdlib.h>
        !            62: 
        !            63: static inline char     *med3 __P((char *, char *, char *, int (*)()));
        !            64: static inline void      swapfunc __P((char *, char *, int, int));
        !            65: 
        !            66: #define min(a, b)      (a) < (b) ? a : b
        !            67: 
        !            68: /*
        !            69:  * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
        !            70:  */
        !            71: #define swapcode(TYPE, parmi, parmj, n) {              \
        !            72:        long i = (n) / sizeof (TYPE);                   \
        !            73:        register TYPE *pi = (TYPE *) (parmi);           \
        !            74:        register TYPE *pj = (TYPE *) (parmj);           \
        !            75:        do {                                            \
        !            76:                register TYPE   t = *pi;                \
        !            77:                *pi++ = *pj;                            \
        !            78:                *pj++ = t;                              \
        !            79:         } while (--i > 0);                             \
        !            80: }
        !            81: 
        !            82: #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
        !            83:        es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
        !            84: 
        !            85: static inline void
        !            86: swapfunc(a, b, n, swaptype)
        !            87:        char *a, *b;
        !            88:        int n, swaptype;
        !            89: {
        !            90:        if(swaptype <= 1) 
        !            91:                swapcode(long, a, b, n)
        !            92:        else
        !            93:                swapcode(char, a, b, n)
        !            94: }
        !            95: 
        !            96: #define swap(a, b)                                     \
        !            97:        if (swaptype == 0) {                            \
        !            98:                long t = *(long *)(a);                  \
        !            99:                *(long *)(a) = *(long *)(b);            \
        !           100:                *(long *)(b) = t;                       \
        !           101:        } else                                          \
        !           102:                swapfunc(a, b, es, swaptype)
        !           103: 
        !           104: #define vecswap(a, b, n)       if ((n) > 0) swapfunc(a, b, n, swaptype)
        !           105: 
        !           106: static inline char *
        !           107: med3(a, b, c, cmp)
        !           108:        char *a, *b, *c;
        !           109:        int (*cmp)();
        !           110: {
        !           111:        return cmp(a, b) < 0 ?
        !           112:               (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
        !           113:               :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
        !           114: }
        !           115: 
        !           116: void
        !           117: qsort(a, n, es, cmp)
        !           118:        void *a;
        !           119:        size_t n, es;
        !           120:        int (*cmp)();
        !           121: {
        !           122:        char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
        !           123:        int d, r, swaptype, swap_cnt;
        !           124: 
        !           125: loop:  SWAPINIT(a, es);
        !           126:        swap_cnt = 0;
        !           127:        if (n < 7) {
        !           128:                for (pm = a + es; pm < (char *) a + n * es; pm += es)
        !           129:                        for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
        !           130:                             pl -= es)
        !           131:                                swap(pl, pl - es);
        !           132:                return;
        !           133:        }
        !           134:        pm = a + (n / 2) * es;
        !           135:        if (n > 7) {
        !           136:                pl = a;
        !           137:                pn = a + (n - 1) * es;
        !           138:                if (n > 40) {
        !           139:                        d = (n / 8) * es;
        !           140:                        pl = med3(pl, pl + d, pl + 2 * d, cmp);
        !           141:                        pm = med3(pm - d, pm, pm + d, cmp);
        !           142:                        pn = med3(pn - 2 * d, pn - d, pn, cmp);
        !           143:                }
        !           144:                pm = med3(pl, pm, pn, cmp);
        !           145:        }
        !           146:        swap(a, pm);
        !           147:        pa = pb = a + es;
        !           148: 
        !           149:        pc = pd = a + (n - 1) * es;
        !           150:        for (;;) {
        !           151:                while (pb <= pc && (r = cmp(pb, a)) <= 0) {
        !           152:                        if (r == 0) {
        !           153:                                swap_cnt = 1;
        !           154:                                swap(pa, pb);
        !           155:                                pa += es;
        !           156:                        }
        !           157:                        pb += es;
        !           158:                }
        !           159:                while (pb <= pc && (r = cmp(pc, a)) >= 0) {
        !           160:                        if (r == 0) {
        !           161:                                swap_cnt = 1;
        !           162:                                swap(pc, pd);
        !           163:                                pd -= es;
        !           164:                        }
        !           165:                        pc -= es;
        !           166:                }
        !           167:                if (pb > pc)
        !           168:                        break;
        !           169:                swap(pb, pc);
        !           170:                swap_cnt = 1;
        !           171:                pb += es;
        !           172:                pc -= es;
        !           173:        }
        !           174:        if (swap_cnt == 0) {  /* Switch to insertion sort */
        !           175:                for (pm = a + es; pm < (char *) a + n * es; pm += es)
        !           176:                        for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 
        !           177:                             pl -= es)
        !           178:                                swap(pl, pl - es);
        !           179:                return;
        !           180:        }
        !           181: 
        !           182:        pn = a + n * es;
        !           183:        r = min(pa - (char *)a, pb - pa);
        !           184:        vecswap(a, pb - r, r);
        !           185:        r = min(pd - pc, pn - pd - es);
        !           186:        vecswap(pb, pn - r, r);
        !           187:        if ((r = pb - pa) > es)
        !           188:                qsort(a, r / es, es, cmp);
        !           189:        if ((r = pd - pc) > es) { 
        !           190:                /* Iterate rather than recurse to save stack space */
        !           191:                a = pn - r;
        !           192:                n = r / es;
        !           193:                goto loop;
        !           194:        }
        !           195: /*             qsort(pn - r, r / es, es, cmp);*/
        !           196: }

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